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But it is also be carne "en mechas", a way of preparing some beef cuts which, after cooking them, are shredded into "threads" of meat and served in different ways: with tomato sauce, in arepas, with rice... See Wikipedia article.

You stuff things (normally fat, but also ham, nuts...) into carne mechada with an aguja de mechar ("barding needle" or lardoir) like this:

Completing @MikMik's answer, I must say that in my part of the world (western Andalusia), the carne mechada (usually pork loin) isn't normally stuffed nor shreded into threads, just cooked with certain seasonings and condiments, while still retaining the name mechada (pronounced mechá).